function class(super)     local mt = {__call = function(_c, ...)         local function create(_c, _o, ...)             if _c.__super then create(_c.__super, _o, ...) end             if _c.__ctor then _c.__ctor(_o, ...) end             return _o         end         local _o = create(_c, {}, ...)         return setmetatable(_o, _c)     end}     mt.__index = super or mt     return setmetatable({__super = super}, mt) end ---------------------------------------------------------------------- A = class() function A:__ctor(s)     self.i = 123     self.j = 333     print('A ctor', s) end local a = A('a') print(a.i, a.j) -- B继承A B = class(A) function B:__ctor(s)     self.i = 444     print('B ctor', s) end local b = B('b') print(b.i, b.j)